Financial infidelity is the root cause of many crumbling unions, says family law attorney Steven Mindel.

"More marriages fall apart for financial reasons than for fidelity reasons," Mindel says. "Fundamentally, marriages are built on trust and anytime you breach the trust of the other party, it damages the relationship. Getting married is like the merging of two enterprises."

Nearly half of divorced or separated U.S. adults said they regret not discussing their personal finances before taking their vows, according to a survey by Couponcabin.com.

With Mindel's help and a host of other family law and finance experts, we've rounded up a list of some of the most damaging money lies spouses can tell.

1/

You're heir to a huge fortune but kept it mum.

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Mindel says hiding details of an inheritance or trust fund is one of the most common lies he's seen in clients.

It's not a wise move, especially since it's easy enough for a partner to find out if they pay attention to your tax returns, Mindel points out.

Unless you also plan on also lying to the IRS about the trust fund, you'll have to report your monthly checks with the rest of your taxable income.

You keep a secret bank account for yourself.

If you've got money that's off the books, such as cash you're earning from a freelance or part-time job, it's not OK to stash it in a secret account your partner doesn't know about.

"People get pissed when they find statements about hidden accounts," says family law attorney Jennifer Deniger.

"A lot of married couples don't understand the concept of joint property and they think that if they get divorced, then anything they have in a solo account is theirs to keep. But the joke is on them because the (spouse) still gets half."

4/

You were laid off but too ashamed to fess up.

Lying about job loss often occurs because spouses are either ashamed of their failure or are convinced they'll be able to nab a new gig before their partner notices.

"We don't see it very often but you hear about people that are shocked to hear that their spouse has been covering up a job loss," Mindel says. "They leave early to go to work but don't have a job to go to."

5/

You're out playing the slots when you're supposed to be grocery shopping.

You've got kids from a previous marriage.

"I know of a situation where a husband did not tell a wife that he had previous children and was not paying child support," Wagner says. "The (new) wife ended up being sued because they had a joint account."

9/

You're underwater on your mortgage and facing foreclosure.

Andrew Scharge, founder of Money Crashers, says this is an especially easy lie for a stay-at-home spouse, who can cover up bill collector mail and phone calls.

"The difficult result is the loss of their home, which will come as a shocking surprise to the spouse who was unaware of their financial situation," he says.

"It can be a challenge to deal with a lying spouse, but ultimately, if the couple does not deal head-on with these issues of trust by implementing some money management tips for married couples, the couple will very likely separate or divorce."

10/

You've been hiding an online shopping addiction.

AP

Compulsive spending habits can wreck a marriage, especially if they're kept under cover. Some partners go as far as to send shipments to friends' houses or the office as a cover-up.

"Compulsive spenders lie about the amount of money they spend, how often they spend money and what they spend money on," says Paul Hokemeyer, a licensed marriage and family therapist.

"It destroys relationships because the non spending partner typically has no clue over the extent of the spending that's going on and wakes up to a bankruptcy or unmanageable debt that in turns makes them feel betrayed, taken advantage of and humiliated."